Sub-Torcular Collateral Channel Classification in Venous Hypertension and Stenting Results

Introduction/Purpose Venous sinus stenosis is a cause of venopathic intracranial hypertension and is treated with venous sinus stenting (VSS). While superficial collaterals are well described, venous pathways below the torcula remain poorly characterized. We aimed to classify these deep collaterals and assess their behavior following stenting. Materials/Methods Consecutive adults undergoing VSS with high‐resolution venography (2024‐2025) were retrospectively reviewed. Collaterals were categorized as Type 1 (torcula/transverse), Type 2 (sigmoid), or Type 3 (jugular bulb) (Figure 1). Pre‐ and post‐stent venograms were qualitatively assessed and quantitatively analyzed with image segmentation and alignment to measure area change and Jaccard similarity indices (Figure 2). Results Forty‐one patients (48 procedures; 92% female; mean age 38.5) were included. Sub‐torcular collaterals were present in 95%: Type 1 in 42%, Type 2 in 6%, and Type 3 in 67%, with multiple types in 22%. Symptoms did not differ significantly by collateral type. Qualitatively, Type 1 collaterals often resolved completely or partially, while Type 3 collaterals persisted in 76% (p<0.001). Quantitatively, percent area reduction was similar (13.9% vs 13.6%, p=0.73), but Jaccard indices were higher for Type 3 (68.1 vs 57.0, p=0.037), indicating greater persistence. Conclusion Sub‐torcular venous collaterals are common in patients with venous outflow obstruction. Jugular bulb collaterals persist more frequently after stenting than torcular collaterals, suggesting differential hemodynamic adaptation. These findings establish a reproducible classification system and highlight a previously under‐recognized aspect of cerebral venous circulation.